This invention relates to an improved method of filling elongated generally lineal channels with polymeric foam using an application gun which directs a thin elongated stream of liquid foamable polymeric resin generally coincident with the longitudinal axis of the channel through an open end of the channel. More specifically, the method of this invention utilizes a laser light fixed relative to the foam application gun which assures accurate alignment of the stream of foamable polymeric resin even though the operator's view of the inside of the channel is blocked by the application gun. Extruded elongated polyvinyl chloride (PVC) channels are commonly used by the building industry for various applications including, for example, the lineals surrounding a window opening. The extruded lintels are commonly available in twelve and sixteen foot lengths and generally include two or more parallel channels. Preformed or precut foam PVC cores are telescopically inserted into the channels to provide a thermal barrier, reduce sound attenuation and impede air infiltration. The channels to be filled have a cross-sectional area generally ranging from about 0.5 square inches to 2 square inches or greater. It is generally difficult, however, to use a preformed foam core because the shape of the channels may be complex and the shape may vary from channel to channel.
The present commercial methods of filling channels of an extruded lineal with liquid foamable resin result in substantial voids throughout the length of the channels, reducing the advantages of filling the channels with foam. These methods require movement of either the application gun or the lineal, requiring two or three operators. In one method, for example, a conventional foam application gun, such as Gusmer Model D Spray Gun or AR-25 pour gun, is fitted with a metal tubular extension having a length of about three feet or longer. The extension is inserted in one open end of the lineal channel and liquid foamable polyurethane foam is then poured into the channel. The channel is then moved away from the gun to fill one-half of the channel of the lineal with polyurethane foam. The process is then repeated from the opposite end of the lineal to fill the channel with polyurethane foam. In a second commercial method, a polyurethane pour gun is fitted with a flexible house which is inserted several feet into the lineal channel. The hose is then withdrawn as the liquid polyurethane foam is poured into the lineal channel, allowing the filling of the lineal channel from one end. The rate of withdrawal of the hose must be accurately controlled and one operator generally withdraws the hose as the second operator operates the pour gun. Both methods, however, result in substantial voids throughout the lineal channel or inconsistent filling and both methods generally require at least two operators.
U.S. Pat. No. 5,129,975 assigned to the assignee of the present application discloses a method of substantially completely filling elongated channels with polymeric foam by directing a stream of liquid foamable polymeric resin into the channel from one end. In the preferred embodiment of the method disclosed in this patent, the lineal is first oriented at an angle generally about 60.degree. and the application gun is then operated to direct a thin elongated stream of foamable polyurethane into the lineal from the top open end, preferably coincident with the longitudinal axis of the channel, such that the stream impinges at or near the bottom of the channel and the foam rises upwardly through the channel and fills the channel. The primary problem with this method, however, is that the application gun covers the open end of the channel such that the operator cannot accurately align the stream of liquid foamable resin into the channel, particularly in mass production applications. If the nozzle of the application gun is not accurately aligned with the longitudinal axis of the channel, the stream will impinge the side wall of the channel blocking the stream and preventing complete filling of the channel. This is a difficult problem particularly in mass production applications because the channels are relatively small in cross-section as set forth above and the length of the channel is generally twelve or sixteen foot in length. There is therefore a need to provide a simple method of accurately aligning the application gun such that the stream of liquid foamable polymeric resin extends to at least near the end of the channel to completely fill the channel. The method of filling elongated channels of this invention solves this problem by assuring accurate alignment of the application gun with the longitudinal axis of the channel.